Method and means for bending wood



Decl0, 1929- w. H. BERGMANN METHOD AND MEANS FOR BENDI'NG`wooD Filed July 27, 1927 2 Sheets-Sheet l Dec. l0, 1929. w. H. BERGMANN METHOD AND MEANS FOR BENDIN'G WOOD `2 Sheets-Sheet `2 Filed July 27, 1927 Jwenlax/ WILL/AM H, Bmg/"ANN,

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WILLIAM I-I. BERGMANN, OF PIQUA, OHIO, ASSIGNOR Patented Dec. 10, 1929 UNITED STATES PATENT OFFICEA T0 THE AMERICAN `FORK & HOE

COMPANY, OF CLEVELAND, OHIO, A CORPORATION OF OHIO METHOD AND MEANS FOR BENDING WOOD Application led July 27, 1927. Serial No. 208,710.

My invention relates to a method and means for bending wood.

In the bending of pieces of wood into various shapes, as in the manufacture of wooden handles and other articles wherein it is necessary to impart a permanent curvature to the wooden member, serious diiiiculties are experienced in the bending operations, resulting in substantial losses due to breakage, there being an attendant large amount of waste and loss of time.

The present invention seeks to overcome these diiific'ulties and seeks further to provide a method and means whereby pieces of wood may be bent without material loss due to breaking of the wooden parts.

It may readily be seen that when a piece of wood is vbent there are two forces being exerted upon the wood. One of these is a stretching force'or a tension exerted upon the fibers disposed nearer one surface of the wooden piece and a `compressional force exerted on those nearer the opposite surface of the piece. .The rst of these forces tends to stretch the fibers of the wood and to pull the grain apart, separating the fibers while the second compresses the fibers longitudinally and closes the grain, bringing the fibers closer together. The stretching eort will quickly reach the breaking point of the fibers unless `care is taken, and even with the highest degree of care it frequently happens that a large amount of breakage results.

The method involved in the present case depends upon supporting the wood at its bending point so that undue spreading of the fibers is avoided, and the method also provides means for relieving the tensional and compressional stresses imparted upon the wood by forming a compound curve of such form that there will be a substantial relief of these forces after the wood is bent.

The invention will be more apparent by reference to the accompanying drawings, in which Figure l represents a view showing a piece of wood in operative position in the bending means.

Figure 2 is a view of the bending apparatus with a portion of the piece of wood being bent inserted in the device.

Figure 3 is an elevation of one end of the bending device showing `in section a piece of wood inserted therein.

Figure 4 is a view ofa modified form of the device showing a piece of wood to be bent inserted therein.

Figure 5 is a detail viewof the device shown in Figure 4 with a portion of the wooden `piece inserted therein, being illustrated to show the manner in which the wood is shaped.

Referring to Figure l, the numeral l represents a table which is designedto hold the bending mechanism and the wooden piece, this table being provided with a member 2, against which the bending means is adapted to rest, the member 2 being provided with beveled portion 3 adapted to engage the bending member, and to secure the same into position.

This bending member is illustrated generally as shown at 4, and a piece of wood 5 is shown inserted therein, the piece 5 being a piece of such a nature as is generally made into handles for shovels, although it will be understood that any desired form may be bent by the method and means herein described.

The table l is also provided with a clampingmeans 6 to hold the piece 5 in position, but while holding the same tightly against lateral displacement will nevertheless permit longitudinal movement-of the piece of wood. This member 6 :may be of any desired form which is found adaptable for use.

Engaging the end of thekpiece 5 is the member 7 which is a mechanism adapted to impart a continuous thrusting action upon the y piece 5, the member 7 taking any desired form, which will be apparent to a worker in this art, and-may beoperated by any desired means, as by a pneumatic driver illustrated in part at 8.

It will be seen that the part 4 consists of two members, an inner member 9 vto which is pivoted the movable members 10 and l0, the configuration of which corresponds in general to the configuration of the inner member 9. The members 10 and 10L are pivotally mounted upon the inner member 9 at l1 and 11a. The member 9 consists of a relatively heavy metallic piece, conveniently formed as a frame with a reinforcing cross piece 12, adapted to engage the retaining member 2 which takes the thrust. The member 9 is shaped as shown, the two sides being bent into the form of a compound curve in order to bring about their point of contact. It will thus be seen that from the point 9b the frame 9 flares outwardly until it reaches a point approximately adjacent the cross piece 12 and then each side of the frame 9 is bent inwardly until the sides become substantially straight and parallel in the portions 9a, thus giving the frame the general shape of the letter A inverted, the sides of which are bent in a compound curve. The members 10 and 10a have a configuration similar to that of the inner piece 9 but are so formed as to leave a recess extending along the length of the sides of the member 9, the depth of this recess be; in@ regulated by the degree of pivoting permitted by the members 11 and 11u. The side members 10 and-10a are spaced apart from the frame 9v at the pivots 11 and 11a, but engage the frame 9 at the point thereof, thus forming a chamber normally tapering from the top to the point of the frame. It will therefore be seen that wood of various sizes may be inserted'into this chamber. When in operation the member 4 is secured in position, a piece of wood inserted between the members 10 and 10a, which are so flanged as to provide a pair of jaws to engage the piece of wood, the jaws being clamped against the side of the wood, as shown at 13, to prevent the lateral displacement of the said jaws. Longitudinal movement of the wood is permitted, however.

The piece of wood is initially provided with a slot shown at 14, extending from one end, to receive, the point ofthe member 9. The wood is then Asoftened and prepared for bending by steaming and/or by immersion in water, in the usual manner, and then isfitted into the jaws and the wood is secured against lateral displacement by the clamping means 6. Power is then applied to the member 7 and the wood is then forced up between the member 9 and the members 10 and 10, and thereby caused to take the configuration of these members.

In the modified form shown in Figures 4: and 5 there are provided pivoted members 10b and 10c, these members being pivoted together at the point 11b, this pivot 11b determining the amount of space between the members 10b and 10c, these members being formed to provide a recess between them which will receive the desired sizeof wood.

y The member 5a is secured as previously described, and power is applied to it by the members 7a and 8a, as previously described,

kthis resulting in the wood being forced into the compound bend corresponding to the configuration of the members 10b and 10. The

bending member is supported at 12a, as shown in Figures 4 and 5, the support 12a resting against projection 2 of the table.

It will thus be seen that the piece of wood is supported firmly at its portions of bending, and that the gra-in is prevented from separating from its interlocking fibers because of the complete support of the wood on substantially all areas subject to strain during and after the bending operation. Further, the nature of the compound curve imparted to the wood relieves the stretchingl and compressional forces of the wood, the wood being so bent that the compressional area is adjacent a stretched area in each case, and also a stretched area is adjacent the compressed area, as will be extent in the lower portions of the wood. The adjacent compressed and stretched areas will tend to neutralize each other and thereby, to some extent, relieve the tension which will exist in the wood. The stretching forces are also relieved by the thrust under which the wood is forced into the form, the stretching forces opposing the thrust being reduced by an amount dependent upon the thrusting force and the sectional area of the wood.

The wood in the bending device is then dried, and after the drying it is removed and it will be found to be permanently bent in the shape conforming to the conguration of the bending means.

It is believed that the operation and the apparatus employed for the operation will be readily understood from the drawings and the specification, it being understood that it is desired to comprehend within my invention such modications as may be clearly embracedfwithin my claims and the scope of my invention.

Having thus fully described my invention, what I claim as new and desire to secure by Letters Patent, is:

1. A device for bending wood comprising a fixed member adapted to divide the wood into two portions, the said member being outwardly fiared and then bent inwardly until the sides are substantially straight and parallel, reinforcing means for the said member; a plurality of members pivotally mounted on the said fixed member, the shape of the pivoted members conforming to that of the said fixed member, thereby defining a chamber between each of the pivoted members and the fixed member, the said chamber having the same configuration as the members and being adapted to'receive a piece of wood, the shape of the members being such as to assure a firm support for the wood at the areas of bending, and to relieve the strains within the wood, thereby preventing breakage of the said wood.

2. A device for shaping wood comprising a fixed central member and two side members, the said central member being substantially in the form of an inverted A with compound curved sides, the side members being substantially the same configuration and pivotally mounted upon the central member, the side members being laterally spaced from the side arms of the central member except at the pivots, the side members being longitudinally recessed along their inner sides, thereby forming a pair of Wood guiding and supporting chambers of generally S-form, adapted to receive the two arms of a split piece of wood thrust longitudinally therein, and to firmly support the same at the areas of bending.

3. A device for bending the split separated ends of a piece of wood having a slot extending from one of its ends, comprising a centrally wedge-shaped member, and a pair of side members disposed on either side thereof, said side members and the central member being longitudinally recessed on their opposing faces so as to present a pair of divergent passages for the reception of the said split separated wood ends, said side members being relatively hinged at one end of each so as to permit outward swivelling movement of the opposite ends to permit ready removal of a wood piece formed in the divergent passages. 4. A device for bending the split separated ends of a piece of wood having a slot extending from one of its ends, comprising a centrally wedge-shaped member, and a pair of side members disposed on either side thereof, said side members and the central member being longitudinally recessed on their opposing faces so as to present a pair of divergent passages for the reception of the said split areas of bending, and to relieve the strains within the Wood, thereby preventing breakage of the said wood. l

6. A device for forming split wood handles, comprising a member of substantially wedge form having sides outwardly flared from its pointed end and which are substantially straight and parallel to each other adjacent its other end, a pair of oppositely disposed elements pivotally mounted on opposite sides of the enlarged end of said member, said member, side walls and the inwardly disposed opposing walls of said pivoted elements being so formed as to define an elongated chamber between each of said pivoted elements and said member, said member adapted to split separate an end of a wood shaft, each cham ber adapted to receive one of the split separate shaft ends, the shape of said member and said elements being such as to insure a firm support on all sides of the wood ends at the areas of bending and to support the wood against internal strains to prevent breakage of the said split separated end.

In testimony whereof, I affix my signature.

WILLIAM H. BERGMANN.

separated wood ends, said side members being y relatively hinged at one end of each so as to permit outward swivelling movement of the opposite ends to permit ready removal of a wood piece formed in the divergent passages, both of said passages longitudinally being of a eompoundly curved form when being relatively oppositely turned.

5. A device for forming split wood handles comprising a fixed member of wedge form adapted to divide an end of a wood shaft into two split separated portions, the sides of said member being outwardly flared from its pointed end and extending substantially straight and parallel to each other adjacent its other end, reenforoing means connecting the sides of the said member, a pair of oppositely disposed members pivotally mounted on opposite sides of the enlarged end of the fixed member and each extending along a different one of its sides, the shape of the inner walls of the pivoted members conforming to the outer side walls of the fixed member, to define an elongated chamber between each of the pivoted members and the fixed member` each chamber adapted to receive a split separated end of the shaft, the shape of the members being such as to assure a firm sup port on all sides for the wood ends at the 

